1. Field of the Invention
The present invention relates to a data printing apparatus for a camera and, more particularly, to a data printing apparatus for a camera, which can write data such as a photographing date on a film of the camera as a photographing medium.
2. Description of the Related Art
Conventionally, a data printing apparatus which comprises light-emitting elements defining numerals and characters necessary for printing, e.g., a date, and prints a date on a still film is known. On the other hand, as shown in FIGS. 16A and 16B or FIG. 17, a data printing apparatus which drives light-emitting elements in synchronism with travel of a film, and prints, e.g., a date on the traveling film is known. More specifically, in FIG. 16A, when a photographed film is wound up from a patrone 45 around a take-up spool 44, a position where data such as a date is written is detected by a position detector 41. When the write position is reached, a driver 42 is driven to turn on a 7-segment display 43 for a short period of time, thereby printing numerals shown in FIG. 16B on a predetermined position on the film. In FIG. 17, LEDs 49a, 49b, . . . , 49g, and a focusing lens 48 are arranged adjacent to a film 46, and when the film 46 is wound up upon completion of a photographing operation, the LEDs 49a, 49b, . . . , 49g are dynamically turned on, thereby printing desired data on the film.
A data writing apparatus of this type is disclosed in, e.g., Published Examined Japanese Patent Application No. 57-55131, Published Unexamined Japanese Patent
Application No. 59-74537 (an arrangement disclosed in these references is shown in FIG. 16A), Published Examined Japanese Patent Application No. 61-56495 (its arrangement is shown in FIG. 17), and the like. As shown in FIG. 17, when data is printed using an LED dot array, not only numerals but also characters can be printed. In this case, high-resolution moving amount detection, and moving amount control are required to synchronize ON operations of LEDs with movement of a film. More specifically, if one character is expressed by 6.times.8 dots, position detection having a resolution of (width of one character)/6 is required.
In order to print one character, a time given by (necessary LED ON time).times.6 is required, and a film wind-up operation takes much time.
When the 7-segment display is used as shown in FIG. 16A, numerals can only be printed. In this case, moving amount detection requires only a low resolution, and one character can be printed within one print time. However, this means requires 7+1 wiring, seven LEDs, and a driver circuit. The 7-segment LED display unit has predetermined fonts, as shown in FIG. 16B, and since vertical lines of "4" and "1" are offset from the center, these numerals undesirably have offset character intervals. In order to prevent this, two segments must be added to provide a 9-segment numeral display. This countermeasure conflicts with an object for decreasing the number of display segments.